The Generation Mechanism And Controlling Method Of Electromagnetic Noise Of Automobile Claw Pole Alternator

China has entered the automobile society. More and more people begin to enjoy the convenience in work and daily life brought by the car. On the other hand, people’s requirements for comfort sense of driving are getting higher and higher. As the power supply system for automobile electric appliance, claw pole alternator’s vibration and noise problems, especially the electromagnetic vibration and noise began to receive wi-despread attention. The radial electromagnetic force waves generated by the air gap magnetic field acts on the stator core, and makes stator core vibrate and then radiate noise to the surrounding. In this paper, the electromagnetic vibration and noise problem of a bare stator claw pole alternator is studied by using the method of combining theoretical derivation and simulation calculation. Some feasible methods to reduce the electromagnetic noise of the claw pole alternator is proposed.Firstly, according to the relevant parameters of the claw pole alternator, a three-dimensional finite element model of it is established by finite element simulation software to analyze the electromagnetic field in the alternator. The air gap magnetic field results under different operation conditions are obtained. The distribution diagrams of each order harmonic are obtained by using Fourier decomposition. Then the natural frequencies of stator core are calculated by simulation software according to the established model. Thirdly, based on the theory of electromagnetic field, the method based on claw pole surface eccentricity to reduce the radial electromagnetic force is proposed, and the output performances of the modified one have remained stable. The air gap magnetic field and radial electromagnetic force waves of claw pole alternator with different eccentricity distance are calculated, respectively. The optimal pole eccentricity distance is found by calculation. The claw poles are easy deformated while the alternator is on the high-speed operation. The electromagnetic noise is generated with changing length of air gap. Three kinds of methods to reduce the centrifugal distortion and electromagnetic noise through fastening claw poles are put forward. Finally, an experiment platform is designed and the effectiveness of the proposed denoising methods is verified.